Homoepitaxy of ZnO and MgZnO Films at 90 °C

• A simple method to synthesize uniform single crystalline homoepitaxial ZnO and MgZnO films.
• ZnO growth on (0 0 0 1) and (0 0 0 1¯) face resulted in films that are strongly different in their structural and optical quality.
• Single crystalline MgZnO film was fabricated under mild conditions (90 °C and ambient pressure).
• Mg incorporation of nearly 1 mol% was obtained while maintaining single phase wurtzite structure.

The aqueous synthesis of uniform single crystalline homoepitaxial zinc oxide, ZnO, and magnesium zinc oxide, MgxZn1−xO, films under very low temperature conditions at T=90 °C and ambient pressure has been explored. A maximum Mg content of 1 mol% was recorded by energy dispersive spectroscopy. The growth on the polar (0 0 0 1) and (0 0 0 1¯) faces resulted in films that are strongly different in their structural and optical quality as evidenced by high-resolution X-ray diffraction, secondary electron microscopy, and photoluminescence. This is a result of the chemistry and temperature of the solution dictating the stability range of growth-governing metastable species. The use of trisodium citrate, Na3C6H5O7, yielded coalesced, mirror-like homoepitaxial films whereas adding magnesium nitrate hexahydrate, Mg(NO3)2·6H2O, favors the growth of films with pronounced faceting.

Homoepitaxial ZnO films grown from aqueous solution below boiling point of water on a ZnO substrate with off-orientation reveal parallel grooves that are characterized by {1 0 1¯ 1} facets. Adding trisodium citrate yields closed, single-crystalline ZnO films, which can further be functionalized. Alloying with MgO yields MgZnO films with low Mg content only.Figure optionsDownload as PowerPoint slide